Script AI problem (SOLVED)

I wrote this script but when its triggered I get an error saying:

NullReferenceException: Object reference not set to an instance of an object
ReaperAI.Awake () (at Assets/ReaperAI.cs:20)
UnityEngine.GameObject:SetActive(GameObject, Boolean)
ATTACK:OnTriggerEnter(Collider) (at Assets/ATTACK.cs:11)

These are the Scripts:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ReaperAI : MonoBehaviour
{
    Rigidbody m_Rigidbody;
    float m_Speed;

    void Start()
    {
        m_Rigidbody = GetComponent<Rigidbody>();
        m_Speed = -10.0f;
    }

    void Awake()
    {
        m_Rigidbody.velocity = transform.forward * m_Speed;
       
    }
}

and

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ATTACK : MonoBehaviour
{
    public GameObject reaper;

    private void OnTriggerEnter(Collider other)
    {
        reaper.SetActive(true);
    }
}

Please Help!

Sorry, I just forgot the rigidbody.